CHAPTER II. 
GREENHOUSE CONSTRUCTION AND HEATING 
The purpose of this chapter is to discuss the principles of green- 
house construction and heating. The details may be found in 
special books, and in catalogs of manufacturers. 
Greenhouses vs. frames.—Frames are admirably 
adapted to vegetable forcing in the South, but for the 
conditions of northern latitudes, greenhouses are vastly 
superior for most purposes to frames. Their advantages 
are numerous: (1) Heat for forcing purposes can be 
generated cheaper by the burning of coal than by the 
fermentation of manure. (2) All cultural conditions may 
be better controlled or regulated in greenhouses than in 
frames. (3) The labor expenditure on a given area is 
usually much less in greenhouses than in frames. 
(4) Shelter during inclement weather enables the em- 
ployer of labor to follow a prearranged plan, and to utilize 
the time of his workmen fully and economically. (5) In 
the North it is not possible to grow in frames at mid- 
winter such crops as tomatoes and cucumbers. In the 
vicinity of all northern cities greenhouses are rapidly 
taking the place of hotbeds and coldframes, not only for 
the forcing of vegetables, but also for the starting of 
early vegetable plants. Hotbeds and coldframes, how- 
ever, have an important place in the vegetable forcing 
industry, and their uses are discussed on page 387. 
Site and position of house.—Any protection that can 
be afforded by trees, hills, buildings or special wind- 
breaks, without shading the house, will reduce the con- 
sumption of fuel and aid in saving the structure from 
damage by hard windstorms. It is advantageous to build. 
on level land, although gentle slopes are not objectionable. 
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